it is easier to just virtualize the whole damn computer IBM did this starting in the 1960s as a way of providing time-sharing. It became their VM/CMS OS produ

it is easier to just virtualize the whole damn computer IBM did this starting in the 1960s as a way of providing time-sharing. It became their VM/CMS OS product line (VM - hypervisor, CMS - single-user guest OS - but any OS could be the guest, including VM itself) CMS influenced the CP/M microcomputer operating system. So yes, it was not unlike DOS. https://en.wikipedia.org/wiki/VM_(operating_system) https://en.wikipedia.org/wiki/VM_(operating_system)